Surgical treatment for dominant malignant nodules of the isthmus of the thyroid gland: A case control study

• The aim of this study was to identify differences between PTC of the isthmus and the thyroid lobes.
• Another aim was to identify differences between PTC and microcarcinomas located in the isthmus.
• We retrospectively analyzed 2239 patients subjected to total thyroidectomy.
• PTC in the isthmus were more likely to be associated with multifocal disease lymph node involvement and capsule invasion.
• Total thyroidectomy could be considered as an appropriate surgical treatment for isthmic PTC.

BackroundAppropriate surgical treatment of papillary thyroid carcinomas (PTC) located in the isthmus remains controversial. The aim of this study was to evaluate the clinicopathological characteristics of PTC of the isthmus compared to tumors located in the thyroid lobes, to identify differences between PTC and microcarcinomas of the isthmus, and to use these findings to establish total thyroidectomy as an appropriate surgical resection for treating these tumors.MethodsWe retrospectively analyzed 2239 patients subjected to total thyroidectomy. PTC was diagnosed in 575 patients, of whom 521 had dominant malignant nodule located in thyroid lobes and 54 had a dominant carcinoma located in the isthmus. Patients with isthmic PTC were divided in Group A (n = 27) with PTC >10 mm and Group B (n = 27) with microcarcinoma ≤10 mm.ResultsIn univariate analysis, multifocality (p = 0.019), lymph node metastasis (p < 0.001), mean tumor size (p = 0.028) and age ≥45 (p = 0.036) were significantly associated with PTC with dominant nodule in the isthmus. Additional analysis of PTC groups (>10 mm vs ≤10 mm) in isthmus showed that multifocality, bilaterality, histological subtype and lymph node metastasis were not significantly different between the two groups.ConclusionsOur results suggest that PTCs located in the isthmus were more likely to be associated with multifocal disease, lymph node involvement and capsule invasion, than carcinomas in other thyroid regions. Therefore, total thyroidectomy could be considered as an appropriate surgical treatment for papillary carcinomas located in the isthmus regardless of size.